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mtd: spi-nor: otp: return -EROFS if region is read-only

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SPI NOR flashes will just ignore program commands if the OTP region is
locked. Thus, a user might not notice that the intended write didn't end
up in the flash. Return -EROFS to the user in this case. From what I can
tell, chips/cfi_cmdset_0001.c also return this error code.

One could optimize spi_nor_mtd_otp_range_is_locked() to read the status
register only once and not for every OTP region, but for that we would
need some more invasive changes. Given that this is
one-time-programmable memory and the normal access mode is reading, we
just live with the small overhead.

By moving the code around a bit, we can just check the length before
calling spi_nor_mtd_otp_range_is_locked() and avoid an underflow there
if a len is 0. This way we don't need to take the lock either. We also
skip the "*retlen = 0" assignment, mtdcore already takes care of that
for us.

Fixes: 069089acf8 ("mtd: spi-nor: add OTP support")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
This commit is contained in:
Michael Walle 2021-06-07 13:27:43 +02:00 committed by Vignesh Raghavendra
parent d5b813e484
commit 388161ca45
1 changed files with 38 additions and 3 deletions
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41
drivers/mtd/spi-nor/otp.c
View File

@ -249,6 +249,29 @@ out:
return ret;
}
static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs,
size_t len)
{
const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
unsigned int region;
int locked;
/*
* If any of the affected OTP regions are locked the entire range is
* considered locked.
*/
for (region = spi_nor_otp_offset_to_region(nor, ofs);
region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1);
region++) {
locked = ops->is_locked(nor, region);
/* take the branch it is locked or in case of an error */
if (locked)
return locked;
}
return 0;
}
static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
size_t total_len, size_t *retlen,
const u8 *buf, bool is_write)
@ -264,14 +287,26 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
if (ofs < 0 || ofs >= spi_nor_otp_size(nor))
return 0;
/* don't access beyond the end */
total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
if (!total_len)
return 0;
ret = spi_nor_lock_and_prep(nor);
if (ret)
return ret;
/* don't access beyond the end */
total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
if (is_write) {
ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len);
if (ret < 0) {
goto out;
} else if (ret) {
ret = -EROFS;
goto out;
}
}
*retlen = 0;
while (total_len) {
/*
* The OTP regions are mapped into a contiguous area starting